Multilayer ceramic capacitor

ABSTRACT

A multilayer ceramic capacitor includes an external electrode that is unlikely to be peeled. First and second external electrodes each include base layers provided over a ceramic body and including a metal and glass, and Cu plated layers provided over the base layers. The multilayer ceramic capacitor includes a reactive layer. The reactive layer contains about 5 atomic % to about 15 atomic % of Ti, about 5 atomic % to about 15 atomic % of Si, and about 2 atomic % to about 10 atomic % of V.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multilayer ceramic capacitor.

2. Description of the Related Art

In recent years, with the reduction in size and height for electronicdevices such as cellular phones and portable music players, wiringboards mounted on the electronic devices have been progressively reducedin size. Accordingly, multilayer ceramic capacitors mounted on thewiring boards have been also progressively reduced in size and height.

As a method for densely arranging multilayer ceramic capacitors on thewiring boards, for example, it is conceivable that multilayer ceramiccapacitors are built in multilayer printed wiring boards (for example,see Japanese Patent Application Laid-Open No. 2002-203735)

In the case of multilayer ceramic capacitors built in multilayer printedwiring boards as described in Japanese Patent Application Laid-Open No.2002-203735, typically, the outermost layers of external electrodes arecomposed of Cu plated layers. This is intended to suppress damage to theexternal electrodes when via holes for the multilayer ceramic capacitorsare formed by laser light irradiation.

However, when the external electrodes are composed of a laminate bodyincluding a base layer and a Cu plated layer formed over the base layer,there is a problem in that the Cu plating bath dissolves glass of baseelectrode layers composed of a conductive paste, which are formed underthe Cu plated layers, thereby making the external electrodes likely tobe peeled.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a multilayerceramic capacitor with an external electrode which is unlikely to bepeeled.

A multilayer ceramic capacitor according to a preferred embodiment ofthe present invention includes a ceramic body, a first externalelectrode, and a second external electrode. The ceramic body includesfirst and second principal surfaces, first and second side surfaces, andfirst and second end surfaces. The first and second principal surfacesextend in the length direction and width direction. The first and secondside surfaces extend in the length direction and height direction. Thefirst and second end surfaces extend in the width direction and theheight direction. The first external electrode is provided over thefirst end surface, and over each of the first and second principalsurfaces. The second external electrode is provided over the second endsurface, and over each of the first and second principal surfaces. Thefirst and second external electrodes each include a base layer providedover the ceramic body and including a metal and glass, and a Cu platedlayer provided over the base layer. A multilayer ceramic capacitoraccording to a preferred embodiment of the present invention furtherincludes a reactive layer. The reactive layer preferably includes about5 atomic % to about 15 atomic % of Ti, about 5 atomic % to about 15atomic % of Si, and about 2 atomic % to about 10 atomic % of V.

In a multilayer ceramic capacitor according to a preferred embodiment ofthe present invention, the reactive layer is preferably about 2 μm toabout 5 μm in maximum thickness.

In a multilayer ceramic capacitor according to a preferred embodiment ofthe present invention, the glass preferably contains at least one ofB₂O₃ and SiO₂, and at least one selected from the group consisting ofAl₂O₃, ZnO, CuO, Li₂O, Na₂O, K₂O, MgO, CaO, BaO, ZrO₂, SrO, V₂O₅, andTiO₂.

In a multilayer ceramic capacitor according to a preferred embodiment ofthe present invention, the ceramic body preferably contains BaTiO₃.

A multilayer ceramic capacitor according to a preferred embodiment ofthe present invention is preferably about 0.9 mm to about 1.1 mm inlength dimension, about 0.4 mm to about 0.6 mm in width dimension, andabout 0.085 mm to about 0.15 mm in height dimension.

According to various preferred embodiments of the present invention, amultilayer ceramic capacitor with an external electrode which isunlikely to be peeled is provided.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a multilayer ceramic capacitoraccording to a preferred embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of FIG. 1 along the lineII-II.

FIG. 3 is a schematic side view of a multilayer ceramic capacitoraccording to a preferred embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a modification example of a preferred embodimentof the present invention.

FIG. 5 is a schematic cross-sectional view of a portion of a multilayerceramic capacitor according to a modification example of a preferredembodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a portion of a multilayerceramic capacitor according to a modification example of a preferredembodiment of the present invention.

FIG. 7 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a modification example of a preferred embodimentof the present invention.

FIG. 8 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a modification example of a preferred embodimentof the present invention.

FIG. 9 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a modification example of a preferred embodimentof the present invention.

FIG. 10 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a modification example of a preferred embodimentof the present invention.

FIG. 11 is a schematic cross-sectional view of a multilayer ceramiccapacitor according to a modification example of a preferred embodimentof the present invention.

FIG. 12 is a cross-sectional photograph of a reactive layer of a sampleprepared according to an example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to examples. However, the following preferred embodimentswill be provided merely by way of example. The present invention is notlimited to the following preferred embodiments in any way.

In addition, members that have the same or substantially the samefunctions shall be denoted by the same reference symbols in therespective drawings referenced in the preferred embodiments, etc. Inaddition, the drawings referenced in the preferred embodiments, etc. areschematically made. The dimensional ratios or the like between theobjects drawn in the drawings may differ from the dimensional ratios orthe like between real objects. The dimensional ratios or the likebetween the objects may also differ between the drawings. The specificdimensional ratios or the like of the objects should be determined inview of the following description.

As shown in FIGS. 1 through 3, a multilayer ceramic capacitor 1 includesa ceramic body 10. The ceramic body 10 can be formed from, for example,a dielectric ceramic material. Specific examples of the dielectricceramic material include, for example, BaTiO₃, CaTiO₃, SrTiO₃, andCaZrO₃. With the above ceramic material as a main constituent, accessoryconstituents such as, for example, Mn compounds, Mg compounds, Sicompounds, Fe compounds, Cr compounds, Co compounds, Ni compounds, andrare-earth compounds may be added appropriately to the ceramic body 10,depending on desired characteristics of the multilayer ceramic capacitor1.

In the present preferred embodiment, the ceramic body 10 is preferablyin the form of a cuboid. The “form of a cuboid” herein is considered toencompass cuboids with corners or ridges rounded.

The ceramic body 10 includes first and second principal surfaces 10 a,10 b, first and second side surfaces 10 c, 10 d, and first and secondend surfaces 10 e, 10 f. The first and second principal surfaces 10 a,10 b each extend in the length direction L and the width direction W.The first and second side surfaces 10 c, 10 d each extend in the lengthdirection L and the height direction T. The first and second endsurfaces 10 e, 10 f each extend in the width direction W and the heightdirection T.

The multilayer ceramic capacitor 1 is preferably about 0.9 mm to about1.1 mm in length dimension. The multilayer ceramic capacitor 1 ispreferably about 0.4 mm to about 0.6 mm in width dimension. Themultilayer ceramic capacitor 1 is preferably about 0.085 mm to about0.15 mm in height dimension. When the height dimension, lengthdimension, and width dimension of the ceramic body 10 are referred torespectively as DT, DL, and DW, the condition of DT<DW<DL,(1/7)DW≦DT≦(1/4)DW, or DT<about 0.15 mm is preferably met.

As shown in FIG. 2, pluralities of first and second internal electrodes11, 12 that are substantially rectangular are disposed within theceramic body 10. The first and second internal electrodes 11, 12 eachextend in the length direction L and the width direction W. The firstinternal electrodes 11 are extended to the first end surface 10 e, butnot exposed to the second end surface 10 f or the first and second sidesurfaces 10 c, 10 d. On the other hand, the second internal electrodes12 are extended to the second end surface 10 f, but not exposed to thefirst end surface 10 e or the first and second side surfaces 10 c, 10 d.The first internal electrodes 11 and the second internal electrodes 12are alternately provided at intervals mutually in the height directionT. The ceramic portions 10 g provided between the first internalelectrodes 11 and the second internal electrodes 12 can be adjusted to,for example, on the order of about 0.5 μm to about 10 μm in height. Thefirst and second internal electrodes 11, 12 can be adjusted to, forexample, on the order of about 0.2 μm to about 2 μm in height.

The first and second internal electrodes 11, 12 can be composed of anappropriate conductive material. The first and second internalelectrodes 11, 12 can be composed of, for example, a metal such as Ni,Cu, Ag, Pd, and Au, or an alloy containing one of the metals, such as,for example, an Ag—Pd alloy.

A glass layer may be formed on exposed portions of the internalelectrodes at the end surfaces 10 e, 10 f. The formation of the glasslayer on the exposed portions of the internal electrodes 11, 12 ensureresistance to moisture and plating even when the external electrodes 13,14 are insufficiently dense, significantly reduce or prevent ingress ofmoisture from the outside into the ceramic body 10, and improveresistance to moisture and plating.

The first and second external electrodes 13, 14 are provided over theceramic body 10.

The first external electrode 13 is connected to the first internalelectrodes 11. The first external electrode 13 is provided incommunication with the first end surface 10 e, and each of the first andsecond principal surfaces 10 a, 10 b as well as the first and secondside surfaces 10 c, 10 d. It is to be noted that the first externalelectrode may be provided in communication with only the first endsurface and at least one of the first and second principal surfaces in apreferred embodiment of the present invention.

The second external electrode 14 is connected to the second internalelectrodes 12. The second external electrode 14 is provided incommunication with the second end surface 10 f, and each of the firstand second principal surfaces 10 a, 10 b as well as the first and secondside surfaces 10 c, 10 d. It is to be noted that the second externalelectrode may be provided in communication with only the second endsurface and at least one of the first and second principal surfaces in apreferred embodiment of the present invention.

The first external electrode 13 includes a first base layer 13 a and afirst Cu plated layer 13 b. The first base layer 13 a is provided overthe ceramic body 10. The first base layer 13 a can be formed by firing aconductive paste layer formed by applying a conductive paste.

The first base layer 13 a includes a metal and glass. Examples of themetal included in the first base layer 13 a include, for example,appropriate metals such as Ni, Cu, Ag, Pd, Au, and Ag—Pd alloys.

The first base layer 13 a is preferably about 1 μm to about 20 μm inthickness.

The first Cu plated layer 13 b is provided over the first base layer 13a. The surface of the first Cu plated layer 13 b may be at leastpartially oxidized. For example, the first Cu plated layer 13 bpreferably has ridges oxidized. In this case, when the multilayerceramic capacitor 1 is embedded into a wiring board, the oxidizedportions and resin of the wiring board are attached through oxygenbinding, and the adhesion strength between the first external electrode13 and the resin wiring board can be thus increased. It is to be notedthat the effect mentioned above is greater when the entire surface ofthe first external electrode 13 is oxidized.

The first Cu plated layer 13 b is preferably about 1 μm to about 10 μmin thickness.

It is to be noted that the first Cu plated layer 13 b may includemultiple layers instead of one single layer. As just described, when theoutermost layers of the external electrodes 13, 14 are composed of Cuplated films, it becomes possible to use the multilayer ceramiccapacitor 1 as an electronic component built in a multilayer printedwiring board.

In addition, in the case of embedding the multilayer ceramic capacitor 1into a multilayer printed wiring board, there is a need to provide a viahole for electronic component connection in the multilayer printedwiring board, in order to provide electrical connection to the firstexternal electrode 13. This via hole for electronic component connectionis formed with the use of a laser such as a CO₂ laser, for example. Inthe case of forming the via hole with the use of a laser, the firstexternal electrode 13 of the multilayer ceramic capacitor 1 is directlyirradiated with the laser. In this case, when the outermost layer of thefirst external electrode 13 includes the first plated layer 13 b, thelaser can be reflected with a high reflectance. From the foregoing, themultilayer ceramic capacitor 1 is preferred for embedding into amultilayer printed wiring board. When the laser reflectance is low withrespect to the first external electrode 13 of the multilayer ceramiccapacitor 1, the laser may reach even the inside of the multilayerceramic capacitor 1, and damage the multilayer ceramic capacitor 1.

The second external electrode 14 includes a second base layer 14 a and asecond Cu plated layer 14 b. The second base layer 14 a is provided overthe ceramic body 10. The second base layer 14 a can be formed by firinga conductive paste layer formed by applying a conductive paste.

The second base layer 14 a includes a metal and glass. Examples of themetal included in the second base layer 14 a include, for example,appropriate metals such as Ni, Cu, Ag, Pd, Au, and Ag—Pd alloys.

The second base layer 14 a is preferably about 1 μm to about 20 μm inthickness.

The second Cu plated layer 14 b is provided over the second base layer14 a. The surface of the second Cu plated layer 14 b may be at leastpartially oxidized. For example, the second Cu plated layer 14 bpreferably has ridges oxidized. In this case, when the capacitor isembedded into a wiring board, the oxidized portions and resin of thewiring board are attached through oxygen binding, and the adhesionstrength between the second external electrode 14 and the resin wiringboard is thus increased. It is to be noted that the effect mentionedabove is greater when the entire surface of the second externalelectrode 14 is oxidized.

The second Cu plated layer 14 b is preferably about 1 μm to about 10 μmin thickness.

It is to be noted that the second Cu plated layer 14 b may includemultiple layers rather than just one layer.

In addition, in the case of embedding the multilayer ceramic capacitor 1into a multilayer printed wiring board, there is a need to provide a viahole for electronic component connection in the multilayer printedwiring board, in order to provide electrical connection to the secondexternal electrode 14. This via hole for electronic component connectionis preferably formed with the use of a laser such as a CO₂ laser, forexample. In the case of forming the via hole with the use of a laser,the second external electrode 14 of the multilayer ceramic capacitor 1is directly irradiated with the laser. In this case, when the outermostlayer of the second external electrode 14 includes the plated layer 14b, the laser can be reflected at a high reflectance. From the foregoing,the multilayer ceramic capacitor 1 is preferred for embedding into amultilayer printed wiring board. When the laser reflectance is low withrespect to the second external electrode 14 of the multilayer ceramiccapacitor 1, the laser may reach even the inside of the multilayerceramic capacitor 1, and damage the multilayer ceramic capacitor 1.

Multilayer ceramic capacitors are required to have external electrodesthat are unlikely to be peeled. In the multilayer ceramic capacitor 1, areactive layer 20 containing about 5 atomic % to about 15 atomic % ofTi, about 5 atomic % to about 15 atomic % of Si, and about 2 atomic % toabout 10 atomic % of V (see FIG. 11) is preferably provided between theceramic body 10 and the base layers 13 a, 14 a. For this reason, theexternal electrodes 13, 14 are unlikely to be peeled from the multilayerceramic capacitor 1.

It is to be noted that as a cause of the external electrodes beingunlikely to be peeled, for example, it is conceivable that when theceramic body with the base layers formed is immersed in a Cu platingbath in order to form Cu plated layers, glass in the base layers iseluted to decrease the adhesion strength between the base layers and theceramic body. Therefore, when the reactive layer 20 containing about 5atomic % to about 15 atomic % of Ti, about 5 atomic % to about 15 atomic% of Si, and about 2 atomic % to about 10 atomic % of V is formedbetween the ceramic body 10 and the base layers 13 a, 14 a, the reactivelayer 20 which has this composition is formed in such a way that aceramic component of the ceramic body is reacted with a glass componentin the conductive paste layers in firing the ceramic body 10. Thereactive layer 20 has excellent resistance to acids and alkalis, and haslow solubility in Cu plating baths such as a sulfuric acid Cu bath, apyrophosphoric acid Cu bath, and a cyan Cu bath. For this reason, theadhesion strength between the base layers 13 a, 14 a and the ceramicbody 10 is unlikely to be decreased in the case of forming the Cu platedlayers 13 b, 14 b. Accordingly, the external electrodes 13, 14 arebelieved to be unlikely to be peeled on the ceramic body 10.

From the perspective of effective suppression or prevention of peelingof the external electrodes 13, 14 the maximum thickness of the reactivelayer 20 is preferably about 0.5 μm to about 5 μm. The externalelectrodes may be peeled from the ceramic body when the maximumthickness of the reactive layer 20 is smaller than about 0.5 μm, whereasthe deflective strength may be decreased because of a decrease in thestrength itself of the ceramic body when the maximum thickness of thereactive layer 20 is larger than about 5 μm. The glass included in theceramic body preferably includes at least one of B₂O₃ and SiO₂; and atleast one selected from the group consisting of Al₂O₃, ZnO, CuO, Li₂O,Na₂O, K₂O, MgO, CaO, BaO, ZrO₂, SrO, V₂O₅, and TiO₂.

A method for manufacturing the multilayer ceramic capacitor 1 is notparticularly limited. The multilayer ceramic capacitor 1 can bemanufactured, for example, in the following manner.

First, ceramic green sheets are prepared for constituting the ceramicbody 10. Next, conductive paste layers are formed by applying aconductive paste onto the ceramic green sheets. The conductive paste canbe applied by various printing methods such as a screen printing method,for example. The conductive paste may contain a binder and a solventbesides conductive particulates.

Next, a plurality of ceramic green sheets without any conductive pastelayer formed, the ceramic green sheets with conductive paste layersformed to correspond to the first or second internal electrodes, and aplurality of ceramic green sheets without any conductive paste layerformed are stacked in this order, and pressed in the stacking directionto prepare a mother laminate body.

Next, the mother laminate body is cut along a virtual cut line on themother laminate body to prepare a plurality of raw ceramic laminatebodies from the mother laminate body. It is to be noted that the motherlaminate body can be cut with a dicing machine or a pushing machine. Theraw ceramic laminate bodies may be subjected to barrel polishing or thelike to have ridges or corners rounded.

Next, the raw ceramic laminate bodies are subjected to firing. In thisfiring step, the first and second internal electrodes are fired. Thefiring temperature can be set appropriately depending on the types ofthe ceramic material and conductive paste used. The firing temperaturecan be adjusted to, for example, on the order of about 900° C. to about1300° C.

Next, a conductive paste is applied by a method such as dipping to bothends of the fired ceramic laminate bodies (ceramic bodies). Next, theconductive paste applied to the ceramic laminate body is subjected tohot-air drying for 10 minutes at about 60° C. to about 180° C., forexample. Thereafter, the dried conductive paste is baked to form baselayers. The baking temperature is preferably adjusted to, for example,about 780° C. to about 900° C.

The conductive paste for use in the formation of the base layersincludes a metallic powder and SiO₂—B₂O₃-based glass frit, and the glassfrit preferably contains, in terms of oxide, SiO₂: about 10 weight % toabout 50 weight %, B₂O₃: about 10 weight % to about 30 weight %, andV₂O₅: about 1 weight % to about 10 weight %. The glass frit ispreferably contained in about 0.5 weight % to about 10 weight % withrespect to 100 weight % of the metallic powder.

It is to be noted that with the conductive paste layers formed inadvance on the raw ceramic body, the base layers may be subjected toco-firing with the ceramic body and the internal electrodes.

Thereafter, the multilayer ceramic capacitor 1 can be completed byforming one or more plated layers on the base layers.

It is to be noted that in regard to the thickness of the reactive layer20, a cross section was exposed by polishing the side surface of themultilayer ceramic capacitor 1 until the thickness in the widthdirection was reduced to about ½. This cross section was observed with ascanning electron microscope (SEM), and the thickness of the reactivelayer was measured at three points around the center in the heightdirection for each base layer per sample. This measurement was made forfive samples, and the average value for thicknesses at fifteen points intotal was regarded as the thickness of the reactive layer.

SEM Conditions:

Acceleration Voltage: 10 kV

WD: 10.3 mm, ×3000

Now, for example, in such a case as forming an external electrode byfiring conductive paste layers formed by a dip method or the like, aportion of the external electrode located on the first principal surfacemay be different in length from a portion thereof located on the secondprincipal surface. In such a case, the position in the length directionof the thickest portion of the external electrode located on the firstprincipal surface is different from the position in the length directionof the thickest portion thereof located on the second principal surface.Mounting this multilayer ceramic capacitor on a mounting substrate withthe use of a mounter increases the possibility that the multilayerceramic capacitor is cracked.

In this regard, as shown in FIG. 2, the length of the first externalelectrode 13 in the length direction L is referred to as LE1 as viewedfrom the second principal surface 10 b. The length of the first externalelectrode 13 in the length direction L is referred to as LE2 as viewedfrom the first principal surface 10 a. The length of the second externalelectrode 14 in the length direction L is referred to as LE3 as viewedfrom the second principal surface 10 b. The length of the secondexternal electrode 14 in the length direction L is referred to as LE4 asviewed from the first principal surface 10 a. The distance in the lengthdirection L is referred to as LE5 between the thickest portion of thefirst external electrode 13 located on the second principal surface 10 band the outermost end of the first external electrode 13 in the lengthdirection L. The distance in the length direction L is referred to asLE6 between the thickest portion of the first external electrode 13located on the first principal surface 10 a and the outermost end of thefirst external electrode 13 in the length direction L. The distance inthe length direction L is referred to as LE7 between the thickestportion of the second external electrode 14 located on the secondprincipal surface 10 b and the outermost end of the second externalelectrode 14 in the length direction L. The distance in the lengthdirection L is referred to as LE8 between the thickest portion of thesecond external electrode 14 located on the first principal surface 10 aand the outermost end of the second external electrode 14 in the lengthdirection L. The ratio of the absolute value of the difference betweenLE5 and LE6 to the longer one of LE1 and LE2 ((absolute value ofdifference between LE5 and LE6)/(longer one of LE1 and LE2)) is referredto as A1. The ratio of the absolute value of the difference between LE7and LE8 to the longer one of LE3 and LE4 ((absolute value of differencebetween LE7 and LE8)/(longer one of LE3 and LE4)) is referred to as A2.

In the multilayer ceramic capacitor 1, A1 and A2 preferably are eachabout 0.2 or less. For this reason, as can be also seen from the resultsof the following experimental examples, the ceramic body 10 is unlikelyto be cracked in mounting the multilayer ceramic capacitor 1 on amounting substrate with the use of a mounter.

Further, in regard to LE1 and LE3, a cross section is exposed bypolishing the first or second side surface 10 c, 10 d of the multilayerceramic capacitor 1 until the dimension in the width direction W isreduced down to about ½. The dimensions can be obtained by observing thecross section of the multilayer ceramic capacitor from the secondprincipal surface with the use of an optical microscope, and measuringthe length of the external electrode in the center in the widthdirection W.

In regard to LE2 and LE4, a cross section is exposed by polishing thefirst or second side surface 10 c, 10 d of the multilayer ceramiccapacitor 1 until the dimension in the width direction W is reduced downto about ½. The dimensions can be obtained by observing the crosssection of the multilayer ceramic capacitor from the first principalsurface with the use of an optical microscope, and measuring the lengthof the external electrode in the center in the width direction W.

In regard to LE5 to LE8, a cross section is exposed by polishing theside surface of the multilayer ceramic capacitor until the dimension inthe width direction W is reduced down to about ½. This cross section isobserved with the use of an optical microscope to specify the thickestportion of the external electrode located on the principal surface.Next, the dimensions can be obtained by measuring the distance betweenthe thickest portion and the outermost end of the external electrode.

The length in the length direction of the portion of the externalelectrode located on the principal surface can be controlled by thefollowing method. The length in the length direction of the portion ofthe external electrode located on the principal surface can becontrolled by, for example, varying the wettability to the conductivepaste on the ceramic body. The wettability to the conductive paste onthe ceramic body can be varied by, for example, applying a surfactant,or carrying out plasma treatment or the like.

In this regard, as shown in FIG. 8, any of the following conditions (1)to (5) is preferably satisfied in the multilayer ceramic capacitor 1.

Condition 1

The internal electrode located closest to the first principal surface ispreferably composed so that the multilayer ceramic capacitor 1 is about0.9 mm or more and about 1.1 mm or less in length dimension, themultilayer ceramic capacitor 1 is about 0.4 mm or more and about 0.6 mmor less in width dimension, the multilayer ceramic capacitor 1 is about0.085 mm or more and about 0.11 mm or less in height dimension, and theratio (T_(MAX)−T_(MIN))/T of about 1.0% to about 5.0% is met. The targetdimensions of the multilayer ceramic capacitor 1 preferably are about1.0 mm in length dimension, about 0.5 mm in width dimension, and about0.10 mm in height dimension.

Condition 2

The internal electrode located closest to the first principal surface ispreferably composed so that the multilayer ceramic capacitor is about0.9 mm or more and about 1.1 mm or less in length dimension, themultilayer ceramic capacitor is about 0.4 mm or more and about 0.6 mm orless in width dimension, the multilayer ceramic capacitor is about 0.12mm or more and about 0.15 mm or less in height dimension, and the ratio(T_(MAX)−T_(MIN))/T of about 1.3% to about 5.3% is met. The targetdimensions of the multilayer ceramic capacitor 1 preferably are about1.0 mm in length dimension, about 0.5 mm in width dimension, and about0.15 mm in height dimension.

Condition 3

The internal electrode located closest to the first principal surface ispreferably composed so that the multilayer ceramic capacitor is about0.9 mm or more and about 1.1 mm or less in length dimension, themultilayer ceramic capacitor is about 0.4 mm or more and about 0.6 mm orless in width dimension, the multilayer ceramic capacitor is about 0.18mm or more and about 0.20 mm or less in height dimension, and the ratio(T_(MAX)−T_(MIN))/T of about 1.5% to about 5.0% is met. The targetdimensions of the multilayer ceramic capacitor 1 preferably are about1.0 mm in length dimension, about 0.5 mm in width dimension, and about0.20 mm in height dimension.

Condition 4

The internal electrode located closest to the first principal surface ispreferably composed so that the multilayer ceramic capacitor is about0.9 mm or more and about 1.1 mm or less in length dimension, themultilayer ceramic capacitor is about 0.4 mm or more and about 0.6 mm orless in width dimension, the multilayer ceramic capacitor is about 0.21mm or more and about 0.23 mm or less in height dimension, and the ratio(T_(MAX)−T_(MIN))/T of about 1.8% to about 5.9% is met. The targetdimensions of the multilayer ceramic capacitor 1 are about 1.0 mm inlength dimension, about 0.5 mm in width dimension, and about 0.22 mm inheight dimension.

Condition 5

The internal electrode located closest to the first principal surface ispreferably composed so that the multilayer ceramic capacitor is about0.9 mm or more and about 1.1 mm or less in length dimension, themultilayer ceramic capacitor is about 0.4 mm or more and about 0.6 mm orless in width dimension, the multilayer ceramic capacitor is about 0.24mm or more and about 0.30 mm or less in height dimension, and the ratio(T_(MAX)−T_(MIN))/T of about 1.2% to about 6.0% is met. The targetdimensions of the multilayer ceramic capacitor 1 preferably are about1.0 mm in length dimension, about 0.5 mm in width dimension, and about0.25 mm in height dimension.

The multilayer ceramic capacitor 1 preferably meets any of theconditions (1) to (5). For this reason, the ceramic body 10 isreinforced in a preferred manner with the first and second internalelectrodes 11, 12, and the stress applied to the ceramic body 10 whenthe multilayer ceramic capacitor 1 is mounted with the use of a mounteris effectively dispersed. Accordingly, the ceramic body 10 is moreunlikely to be cracked in mounting the multilayer ceramic capacitor 1.Because cracks are unlikely to be generated, the generation of shortcircuit defects in the multilayer ceramic capacitor 1 is effectivelysuppressed or prevented.

Now, in firing the raw ceramic body with the conductive paste layers todefine the first and second base layers 13 a, 14 a, the conductive pastelayers contract more than the raw ceramic body. For this reason, tensilestress is applied to ridges of the ceramic body 10 by contraction ofportions of the conductive paste layers located on the principalsurfaces, and contraction of portions of the conductive paste layerslocated on the end surfaces. This tensile stress makes cracks likely tobe generated from the ridges of the ceramic body 10.

In this regard, as shown in FIG. 9,

a: the distance in the height direction between the first principalsurface and an end in the length direction of an effective portion Ethat refers to a region where the first internal electrodes 11 and thesecond internal electrodes 12 are opposed in the height direction T;

b: the distance in the length direction between the first end surface 10e and the effective portion E in the length direction L;

c: the maximum thickness of a portion of the first base layer 13 aprovided over the first principal surface 10 a;

d: the distance in the length direction between a point of the firstbase layer 13 a over the first end surface 10 c which is furthest fromthe first end surface 10 c and an end of the first base layer 13 a overthe first principal surface 10 a which is closest to the second endsurface 10 f;

e: the maximum thickness of a portion of the first base layer 13 aprovided over the first end surface 10 e; and

f: the height of the ceramic body 10.

In the multilayer ceramic capacitor 1, the ratio (c·d+e·f/2)/(a·b) ispreferably 6 or less, for example. For this reason, with the large(a·b), the ridges of the ceramic body 10 undergo an increase instrength. In addition, the tensile stress applied to the ridges of theceramic body 10 is reduced because the first base layer 13 a is thinwith the small (c·d+e·f/2). Therefore, the multilayer ceramic capacitor1 is unlikely to be cracked from the ridges of the ceramic body 10.

Furthermore, the ratio (c·d+e·f/2)/(a·b) is preferably or more. For thisreason, the first base layer 13 a is not excessively thin. Accordingly,the multilayer ceramic capacitor 1 has excellent resistance to moisture.

The contraction in the case of baking the conductive paste layers islarger than the contraction of the ceramic body in the case of firing.For this reason, tensile stress is likely to be provided by the externalelectrodes to portions of the ceramic body on which ends in the lengthdirection are located, of the external electrodes located on theprincipal surfaces. When tensile stress that is equal to or more than apredetermined value in magnitude is applied to the ceramic body by thetensile stress applied by the external electrodes, the ceramic body iscracked from the contact point between the first principal surface ofthe ceramic body and the end of the external electrode.

In this regard, as shown in FIG. 10, the height of an effective portionE that is a portion of the ceramic body 10 where the first and secondinternal electrodes 11, 12 are provided is referred to as A in theheight direction T. The height of a first outer layer portion that is aportion of the ceramic body 10 located closer to the first principalsurface 10 a than the effective portion E is referred to as B in theheight direction T. The height of a second outer layer portion that is aportion of the ceramic body 10 located closer to the second principalsurface 10 b than the effective portion E is referred to as C in theheight direction T.

In the multilayer ceramic capacitor 1, the ratios A/B and A/C eachpreferably falls within the range of about 0.5 to about 16. For thisreason, the crack generation in the ceramic body 10 is effectivelyreduced or prevented which starts from the contact point between thefirst principal surface 10 a of the ceramic body 10 and the end of theexternal electrode. As the reason therefor, the following reason isconsidered. In the multilayer ceramic capacitor 1, the ratio of theheight of the first and second outer layer portions to the height of theeffective portion E is decreased when the ratios A/B and A/C are eachadjusted in the range of about 0.5 to about 16. More specifically, thefirst and second outer layer portions become relatively smaller inheight. For this reason, when the ceramic body 10 is subjected tofiring, compressive stress applied to the first and second outer layerportions is likely to be increased, due to contraction of the conductivepaste layers to define the internal electrodes. For this reason, forexample, in the case of baking the external electrodes 13, 14 afterfiring the ceramic body 10, the compressive stress of the first andsecond outer layer portions can be increased before baking the externalelectrodes 13, 14. For this reason, tensile stress is less likely to beapplied to the ceramic body 10, even when the conductive paste layers todefine the external electrodes 13, 14 are contracted in baking theexternal electrodes 13, 14. Therefore, the ceramic body 10 is lesslikely to be cracked. Even in the case of simultaneously carrying outfiring for the ceramic body 10 and firing to define the externalelectrodes 13, 14, tensile stress is less likely to be applied to theceramic body 10 for the same reason, and thus believed to be less likelyto be applied to the ceramic body 10.

From the perspective of effectively suppressing or preventing the crackgeneration in the ceramic body 10, when the dimension of the multilayerceramic capacitor 1 in the height direction T is about 50 μm to about150 μm, the ratios of A/B and A/C each preferably fall within the rangeof about 0.6 to about 6. When the dimension of the multilayer ceramiccapacitor 1 in the height direction T is about 150 μm to about 250 μm,the ratios of A/B and A/C each preferably fall within the range of 2 to16.

Further, in the following description, t1 to t3 shown in FIG. 11 will bedefined as follows.

The maximum thickness of a portion of the first external electrode 13located on the first end surface 10 e is referred to as t1 in a crosssection passing through the center in the width direction W andextending in the length direction L and the height direction T.

The maximum thickness of a portion of the first external electrode 13located on the first principal surface 10 a is referred to as t2 in across section passing through the center in the width direction W andextending in the length direction L and the height direction T.

The thickness of the first external electrode 13 on a line passingthrough the point of intersection between a tangent line on a corner ofthe ceramic body 10 and the corner and the point of intersection betweena line along the first principal surface 10 a and a line along the firstend surface 10 e is referred to as t3 in a cross section passing throughthe center in the width direction W and extending in the lengthdirection L and the height direction T.

Preferably, the multilayer ceramic capacitor 1 is embedded into amultilayer printed wiring board, and used. In such a case, themultilayer ceramic capacitor 1 preferably has excellent resistance tomoisture, and excellent adhesion to the resin constituting themultilayer printed wiring board.

The inventor has, as a result of earnest study, conceived of therelationships between the shape of the external electrode, and themoisture resistance of the multilayer ceramic capacitor 1 and theadhesion to the resin. Specifically, the inventor has discovered thatthe relationships among t1 to t3 control the moisture resistance and theadhesion to the resin.

In the multilayer ceramic capacitor 1, the ratio t2/t1 is preferablyabout 0.7 to about 1.0, and the ratio t3/t1 is preferably about 0.4 toabout 1.2. In this case, a multilayer ceramic capacitor is providedwhich has excellent resistance to moisture, and excellent adhesion tothe resin of the multilayer printed wiring board.

An excessively small ratio t2/t1 may result in failure to efficientlyensure the thicknesses of the external electrodes 13, 14 around cornersof the ceramic body 10, and ingress of plating solutions, etc., into themultilayer ceramic capacitor 1, thus decreasing reliability ofresistance to moisture. The excessively large ratio t2/t1 may eliminatethe roundness of the external electrodes 13, 14 around corners of theceramic body 10, and make stress more likely to be concentrated on thecorners, thus decreasing the adhesion between the multilayer ceramiccapacitor 1 and the resin of the multilayer printed wiring board.

An excessively small ratio t3/t1 may result in failure to efficientlyensure the thicknesses of the external electrodes 13, 14 and ingress ofplating solutions, etc., into the multilayer ceramic capacitor 1, thusdecreasing the moisture resistance. The excessively large ratio t3/t1may eliminate the roundness of the external electrodes 13, 14 aroundcorners of the ceramic body 10, and make stress more likely to beconcentrated on the corners, thus decreasing the adhesion between themultilayer ceramic capacitor 1 and the resin of the multilayer printedwiring board.

It is to be noted that t1 to t3 can be measured in the following manner.

Method of t1 Measurement

A cross section is exposed by polishing the first or second side surface10 c, 10 d of the multilayer ceramic capacitor 1 until the height of themultilayer ceramic capacitor 1 in the width direction W is reduced downto about ½. The maximum thickness t1 of the portion of the firstexternal electrode 13 located on the first end surface 10 e can bemeasured by observing the cross section with the use of a microscope.

Method of t2 Measurement

A cross section is exposed by polishing the first or second side surface10 c, 10 d of the multilayer ceramic capacitor 1 until the height of themultilayer ceramic capacitor 1 in the width direction W is reduced downto about ½. The maximum thickness t2 of the portion of the firstexternal electrode 13 located on the first principal surface 10 a can bemeasured by observing the cross section with the use of a microscope.

Method of t3 Measurement

A cross section is exposed by polishing the first or second side surface10 c, 10 d of the multilayer ceramic capacitor 1 until the height of themultilayer ceramic capacitor 1 in the width direction W is reduced downto about ½. The thickness t3 of the first external electrode 13 on theline passing through the point of intersection between the tangent lineon the corner of the ceramic body 10 and the corner and the point ofintersection between the line along the first principal surface 10 a andthe line along the first end surface 10 e can be measured by observingthe cross section with the use of a microscope.

It is to be noted that the arithmetic mean roughness (Ra) at thesurfaces of the external electrodes 13, 14 is preferably larger than thearithmetic mean roughness (Ra) at the surface of the ceramic body 10 inthe present preferred embodiment. More specifically, the ratio of (thearithmetic mean roughness (Ra) at the surface of the ceramic body10)/(the arithmetic mean roughness (Ra) at the surfaces of the externalelectrodes 13, 14) preferably falls within the range of about 0.06 ormore and about 0.97 or less. In the calculation of the arithmetic meanroughness (Ra) at the surface of the ceramic body 10, as a measurementcondition, a laser microscope (Product Name: VK-9510) from KeyenceCorporation is used at a 100-fold lens magnification in a colorultradeep mode set. The range of measurement with the laser microscopeis regarded as a region of 90 μm square including a central portion ofthe principal surface 10 a of the ceramic body 10. Then, the arithmeticmean roughness (Ra) at the surface of the ceramic body 10 is regarded asa value calculated on the basis of the surface roughness measured underthe measurement condition.

On the other hand, in the calculation of the arithmetic mean roughness(Ra) at the surfaces of the external electrodes 13, 14, as a measurementcondition, a laser microscope (Product Name: VK-9510) from KeyenceCorporation is used at a 100-fold lens magnification in a colorultradeep mode set. The range of measurement with the laser microscopeis regarded as a region of 90μm square including a central portion of aportion of the external electrode 13 or external electrode 14 providedon the principal surface 10 a or the principal surface 10 b. Then, thearithmetic mean roughness (Ra) at the surfaces of the externalelectrodes 13, 14 is regarded as a value calculated on the basis of thesurface roughness measured under the measurement condition.

As described above, the arithmetic mean roughness (Ra) at the surfacesof the external electrodes 13, 14 is preferably larger than thearithmetic mean roughness (Ra) at the surface of the ceramic body. Morespecifically, the ratio of (the arithmetic mean roughness (Ra) at thesurface of the ceramic body 10)/(the arithmetic mean roughness (Ra) atthe surfaces of the external electrodes 13, 14) preferably falls withinthe range of about 0.06 or more and about 0.97 or less. For this reason,in the case of closely contacting the resin of the multilayer printedwiring board with the multilayer ceramic capacitor 1 in embedding themultilayer ceramic capacitor 1 into the multilayer printed wiring board,the close contact between the external electrodes 13, 14 and the resinin an embedding concave portion for the capacitor, which is provided inthe multilayer printed wiring board, can be made stronger than the closecontact between the ceramic body 10 and the resin in an embeddingconcave portion for the capacitor, which is provided in the multilayerprinted wiring board. Therefore, gaps are made more unlikely to beproduced between the external electrodes 13, 14 and the resin in theembedding concave portion for the capacitor, which is provided in themultilayer printed wiring board. Accordingly, ingress of moisture intothe gaps is also suppressed or prevented. As a result, reliability ofresistance to moisture is ensured for the multilayer ceramic capacitor1.

Further, methods for achieving the configuration as described aboveinclude, for example, the following method. The ceramic body 10 withdesired arithmetic mean roughness (Ra) can be created by providing thesurface of a mold for use in pressing with appropriate surfaceroughness, if necessary, in the step of pressing the mother laminatebody. It is to be noted that methods for adjusting the arithmetic meanroughness (Ra) at the surface of the ceramic body 10 to desiredarithmetic mean roughness (Ra) include a method of applying a physicalimpact (for example, polishing) to the surface of the ceramic body 10,and a chemical treatment method (for example acid etching).

As shown in FIG. 4, the first external electrode 13 of the multilayerceramic capacitor 1 is preferably configured so that when the distancefrom the position of the maximum thickness on the principal surface 10 aof the ceramic body 10 to the position of the maximum thickness on theend surface 10 e of the ceramic body 10 is referred to as a dimension E(hereinafter, which may be referred to as an “E dimension”), whereas thedistance from the position of the maximum thickness on the end surface10 e of the ceramic body 10 to an edge end of the external electrode 13on the principal surface 10 a of the ceramic body 10 is referred to as adimension e (hereinafter, which may be referred to as an “e dimension”),the ratio E/e preferably is about 0.243 or more and about 0.757 or less.

The dimension E and the dimension e are measured by polishing, for across section, the side surface of the multilayer ceramic capacitor 1 inthe length direction L until reaching about ½ the dimension in the widthdirection, and observing the polished surface with an opticalmicroscope. Specifically, the dimensions are measured by the followingmethods.

(1) Method of E Dimension Measurement

In order to measure the E dimension, the side surface of the multilayerceramic capacitor 1 is polished in the length direction L until thedimension in the width direction W is reduced down to about ½, and thepolished surface is subjected to measurement with an optical microscope.Specifically, in regard to portions located on the principal surface 10a, 10 b, of the external electrodes 13, 14 on the principal surface 10 aor principal surface 10 b of the ceramic body 10, the distances aremeasured from the position of the maximum thickness in the heightdirection T for each of the portions located on the principal surface 10a, 10 b, to the position of the maximum thickness in the lengthdirection L for the external electrode 13, 14 on the end surface 10 e orend surface 10 f of the ceramic body 10. Then, the average for therespective measurement values is regarded as the E dimension.

(2) Method of e Dimension Measurement

In order to measure the e dimension, the side surface of the multilayerceramic capacitor 1 is polished in the length direction L until thedimension in the width direction W is reduced down to about ½, and thepolished surface is subjected to measurement with an optical microscope.Specifically, the distances are measured from the position of themaximum thickness in the length direction L for the external electrode13, 14 located on the end surface 10 e or end surface 10 f of theceramic body 10, to edge ends of portions located on the principalsurface 10 a, 10 b, of the external electrodes 13, 14 located on theprincipal surface 10 a or principal surface 10 b of the ceramic body 10.Then, the average for the respective measurement values is regarded asthe e dimension.

As just described, the formation is preferably achieved so that theratio E/e is about 0.243 or more and about 0.757 or less. Thus, thestress concentration which is generated at corners of the multilayerceramic capacitor 1 is significantly reduced or prevented. As a result,it becomes possible to suppress or prevent peeling that is generatedbetween the corners of the multilayer ceramic capacitor 1 and the resinin the embedding concave portion for the capacitor, which is provided inthe multilayer printed wiring board.

Further, methods for making an adjustment so that the ratio E/epreferably is about 0.243 or more and about 0.757 or less include, forexample, the following method. The ratio E/e can be adjusted byadjusting the rheology of the conductive paste to define the first andsecond base layers 13 a, 14 a, applying surface treatment to the ceramicbody 10, or applying the conductive paste more than once.

As shown in FIG. 5, when the maximum thickness and average thickness ofa portion of the first external electrode 13 located on the principalsurfaces 10 a, 10 b of the ceramic body 10 are denoted respectively byD_(max) and D_(ave), the condition expression ofD_(ave)×250%≧D_(max)≧D_(ave)×120% is preferably satisfied. Likewise,when the maximum thickness and average thickness of a portion of thesecond external electrode 14 located on the principal surfaces 10 a, 10b of the ceramic body 10 are denoted respectively by D_(max) andD_(ave), the condition expression of D_(ave)×250%≧D_(max)≧D_(ave)×120%is preferably satisfied.

It is to be noted that the maximum thickness D_(max) and the averagethickness D_(ave) are measured by polishing the side surface of themultilayer ceramic capacitor 1 in the length direction L until thedimension in the width direction W is reduced down to about ½, andobserving the polished surface with an optical microscope. Specifically,the thicknesses are measured by the following methods.

(1) Method of D_(max) Measurement

In order to measure the maximum thickness D_(max), the side surface ofthe multilayer ceramic capacitor 1 is polished in the length direction Luntil the dimension in the width direction W is reduced down to about ½,and the polished surface is subjected to measurement with an opticalmicroscope. Specifically, the thicknesses of the thickest portions inthe height direction T for each of portions of the external electrodes13, 14 located on the principal surface 10 a or the principal surface 10b are measured for the measurement of the maximum thickness D_(max).Then, the average for the measurement values is regarded as the maximumthickness D_(max)

(2) Method of D_(ave) Measurement

In order to measure the average thickness D_(ave), the side surface ofthe multilayer ceramic capacitor 1 is polished in the length direction Luntil reaching about ½ of the dimension in the width direction W, andthe polished surface is subjected to measurement with an opticalmicroscope. Specifically, the thicknesses in the height direction T forten equal portions obtained by dividing, in the length direction L, eachof the parts of the external electrodes 13, 14 located on the principalsurface 10 a or the principal surface 10 b are measured for themeasurement of the average thickness D_(ave). Then, the average for themeasurement values is regarded as D_(ave).

When the condition expression of D_(ave)×250%≧D_(max)≧D_(ave)×120% issatisfied, the portions of the external electrodes 13, 14 located on theprincipal surfaces 10 a, 10 b are increased in thickness, and theportions of the external electrodes 13, 14 located on the principalsurfaces 10 a, 10 b define and function as cushioning materials, anddisperse the mounting load (stress) applied to the multilayer ceramiccapacitor 1 in suctioning the multilayer ceramic capacitor 1 with ansuction nozzle of a mounting machine (mounter) or pushing the capacitorinto a multilayer printed wiring board. As a result, the generation ofbreakages and cracks is reduced or prevented without concentrating themounting load (stress) on portions of the multilayer ceramic capacitor 1with mechanical strength decreased.

It is to be noted that the maximum thickness D_(max) and the averagethickness D_(ave) is controlled by adjusting the pull-up rate afterdipping the ceramic body 10 in the conductive paste. The pull-up rateafter dipping the ceramic body 10 in the conductive paste is able to beadjusted to, for example, about 20 mm/min or more and about 1000 mm/minor less. The viscosity of the conductive paste is preferably about 10Pa·s or more and about 100 Pa·s or less.

As shown in FIG. 6, in the multilayer ceramic capacitor 1, the platedlayers 13 b, 14 b each preferably include a laminate body including twolayers of Cu plated films. In this case, ingress of the Cu metal of eachCu plated film of the laminate body into the base layer 13 a, 14 a, fromthe surface layer of the base layer 13 a, 14 a even to the position ofabout ⅓ or more the thickness of the base layer 13 a, 14 a may occur. Itis to be noted that in regard to the ingress of the metal of the platedfilm into the base layer 13 a, 14 a, when the side surface (surface LT)of the multilayer ceramic capacitor 1 is polished in the lengthdirection L to about ½ the dimension in the width direction W, and whena line is drawn along a portion of about ⅓ in height from the surfacelayer of the base layer 13 a, 14 a in any observation visual view of 30μm in x-axis and about 30 μm in y-axis at the polished surface,including the base layer 13 a, 14 a located on the principal surface ofthe ceramic body, the metal of the plated film is preferably present inan amount of about 30% or more with respect to the total proportion ofthe metal of the base layer 13 a, 14 a and plated film on the line.

Each Cu plated film is preferably formed with the use of apyrophosphoric acid Cu plating solution or a cyanide Cu platingsolution. These plating solutions with high glass erosion capability,efficiently dissolve the glass contained in the base layer 13 a, 14 a,thus making ingress of the Cu metal of the Cu plated film likely to becaused into the base layer 13 a, 14 a. For this reason, the content rateof Cu is likely to be high in the base layers 13 a, 14 a.

The glass contained in the base layers 13 a, 14 a preferably containsBaO in an amount of about 10 weight % or more and about 50 weight % orless, SrO in an amount of about 10 weight % or more and about 50 weight% or less, B₂O₃ in an amount of about 3 weight % or more and about 30weight % or less, and SiO₂ in an amount of about 3 weight % or more andabout 30 weight % or less. In this case, the glass contained in the baselayers 13 a, 14 a is more easily dissolved in pyrophosphoric acid Cuplating solutions and cyanide Cu plating solutions.

It is to be noted that whether the ingress of the Cu metal of the Cuplated film into the base layers 13 a, 14 a is caused or not can beconfirmed by polishing the side surface of the multilayer ceramiccapacitor 1 in the length direction L until the dimension in the widthdirection W is reduced down to about ½, and observing the polishedsurface with an optical microscope. Specifically, the portion of theexternal electrode 13 located over the first principal surface 10 a isdetermined as “yes” in the case of ingress of the metal of the Cu platedfilm into the base layer 13 a from the surface layer of the base layer13 a even to the position of about ⅓ or more the thickness of the baselayer 13 a, or determined as “no” in the case of no ingress from thesurface layer of the base layer 13 a to the position of about ⅓ or morethe thickness of the base layer 13 a.

Furthermore, the metal thicknesses of the external electrodes 13, 14 arepreferably about 8.7 μm or more and about 13.9 μm or less. The metalthickness refers to a value obtained by measuring the thickness of themetal with a fluorescent X-ray film thickness meter (SFT-9400 from SeikoInstruments Inc.), and converting the measured X-ray Cu amount into afilm thickness. In regard to the measurement point, for example, in thecenter in planar view of the portion of the external electrode 13located over the first principal surface 10 a, the measurement can bemade.

The pyrophosphoric acid Cu plating solution and the cyanide Cu platingsolution have high glass erosion capability, and efficiently dissolvethe glass contained in the base layers 13 a, 14 a. For this reason, theuse of the pyrophosphoric acid Cu plating solution or cyanide Cu platingsolution easily causes ingress of the Cu metal of the Cu plated filminto the base layer 13 a, 14 a. Therefore, the content rate of Cu in thebase layers 13 a, 14 a is greatly improved.

In the case of the formation that causes ingress of the Cu metal of theCu plated film into the base layer 13 a, 14 a from the surface layer ofthe base layer 13 a, 14 a to the position of about ⅓ or more thethickness of the base layer 13 a, 14 a, the Cu content rate is high inthe base layers 13 a, 14 a. Accordingly, in combination with the baselayers 13 a, 14 a and Cu plated films in total, the content rate of Cuper unit thickness is increased to improve the thermal conductivity(heat release performance) of the base layers 13 a, 14 a, and increasethe laser resistance of the external electrodes 13, 14.

Furthermore, in the case of the formation that causes ingress of the Cumetal of the Cu plated film into the base layer 13 a, 14 a from thesurface layer of the base layer 13 a, 14 a to the position of about ⅓ ormore the thickness of the base layer 13 a, 14 a, the difference in levelbetween the surface of the multilayer printed wiring board and thesurfaces of the external electrodes 13, 14 are reduced because theexternal electrodes 13, 14 are reduced in thickness. As a result, thegap between the surface of the multilayer printed wiring board and themounting surface of the ceramic body 10 is narrowed to make peeling lesslikely to be caused between the multilayer printed wiring board and theexternal electrodes 13, 14 and also improve the mechanical strength ofthe component.

EXPERIMENTAL EXAMPLES

A plurality of non-limiting experimental examples of multilayer ceramiccapacitors (approximate target dimensions: 0.1 mm in length dimension,0.5 mm in width dimension, 0.2 mm in height dimension) configured insubstantially the same fashion as the multilayer ceramic capacitor 1were prepared with the conditions shown in Table 1 in accordance withthe manufacturing method described above. The reactive layer was aceramic crystal layer containing about 5 mol % to about 15 mol % of Ti,about 5 mol % to about 15 mol % of Si, and about 2 mol % to about 10 mol% of V. FIG. 12 shows a cross-sectional photograph of the reactivelayer.

The contents for each composition of the respective layers were measuredby examining all of the elements with the use of FE-WDX analysis. Therespective samples were prepared under substantially the sameconditions, except for varying only the parameters shown in therespective tables.

Next, the samples prepared were subjected to the following fixingstrength test. First, the samples were mounted onto a specified testsubstrate with a conductive adhesive, and an end surface of the chip waspushed with a lateral pushing test machine. In that regard, the sampleswith a defect of electrode peeling were determined as “×”, whereas acohesive fracture mode of the conductive adhesive, a fracture mode ofthe ceramic body, and a peeling mode at the interface between theconductive adhesive and the Cu plating were determined as “◯”. Theresults are shown in Tables 1 to 3.

Furthermore, a deflective strength test was carried out in the followingmanner. With a three-point bending tester, a presser was put against thecenters of the samples from the side surface to gradually apply a load,and confirm the fracture mode when the samples were fractured. A ceramiccentrally cracked mode of the ceramic body centrally cracked wasdetermined as “◯”, whereas an electrode end cracked mode of the ceramicbody with an external electrode end cracked was determined as “×”. Thisdeflective strength test was applied to five samples, and even when oneof the samples resulted in “×”, the determination of × was made.

It is to be noted that the results shown in Table 1 correspond toresults obtained when the V content rate was adjusted to about 5 atomic%. The results shown in Table 2 correspond to results obtained when thecontent rates of Si and Ti were both adjusted to about 5 atomic %.

The results shown in Table 3 correspond to results obtained when thecomposition of the reactive layer was adjusted to Ti: about 10 mol %,Si: about 5 mol %, and V: about 5 mol %.

Further, the firing temperature was about 700° C. when no reactive layerwas formed. The firing temperature was about 730° C. when the reactivelayer was about 0.1 μm. The firing temperature was about 750° C. whenthe reactive layer was about 0.5 μm. The firing temperature was 780° C.when the reactive layer was about 1 μm. The firing temperature was about850° C. when the reactive layer was about 5 μm. The firing temperaturewas 900° C. when the reactive layer was about 10 μm. As just described,the thickness of the reactive layer can be controlled by varying thefiring temperature.

TABLE 1 Ti Content (atomic %) 2 5 15 20 Si Content 2 x x x — (atomic %)5 x ∘ ∘ x 15 x ∘ ∘ x 20 — x x —

TABLE 2 V Content (atomic %) 1% 2% 5% 10% Determination x ∘ ∘ ∘

TABLE 3 Thickness of Reactive Layer (μm) 0 0.1 0.5 1 5 10 FixingStrength Evaluation 5/5 4/5 0/5 0/5 0/5 0/5 (The Number of x Samples/TheTotal Number of Samples) Deflective Strength Evaluation ∘ ∘ ∘ ∘ ∘ x

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A multilayer ceramic capacitor comprising: aceramic body including first and second principal surfaces extending ina length direction and a width direction, first and second side surfacesextending in the length direction and a thickness direction, and firstand second end surfaces extending in the width direction and thethickness direction; a first internal electrode extending in the lengthdirection and the width direction, provided in the ceramic body, andexposed at the first end surface; a second internal electrode extendingin the length direction and the width direction, provided in the ceramicbody, exposed at the second end surface, and the second internalelectrode facing the first internal electrode in the height directionwith a ceramic portion interposed therebetween; a first externalelectrode provided over the first end surface, and over a portion ofeach of the first and second principal surfaces; and a second externalelectrode provided over the second end surface, and over a portion ofeach of the first and second principal surfaces; wherein the first andsecond external electrodes each includes a base layer provided over theceramic body and containing a metal and glass, and a Cu plated layerprovided over the base layer; and a boundary layer is provided betweenthe base layer and the ceramic body, the boundary layer containing about5 mol % to about 15 mol % of Ti, about 5 mol % to about 15 mol % of Si,and about 2 mol % to about 10 mol % of V.
 2. The multilayer ceramiccapacitor according to claim 1, wherein the boundary layer is about 0.5μm to about 5 μm in maximum thickness.
 3. The multilayer ceramiccapacitor according to claim 1, wherein the glass contains at least oneof B₂O₃ and SiO₂ and at least one of Al₂O₃, ZnO, CuO, Li₂O, Na₂O, K₂O,MgO, CaO, BaO, ZrO₂, SrO, V₂O₅, and TiO₂.
 4. The multilayer ceramiccapacitor according to claim 1, wherein the multilayer ceramic capacitoris about 0.9 mm to about 1.1 mm in length dimension, about 0.4 mm toabout 0.6 mm in width dimension, and about 0.085 mm to about 0.15 mm inheight dimension.
 5. The multilayer ceramic capacitor according to claim3, wherein the multilayer ceramic capacitor is about 0.9 mm to about 1.1mm in length dimension, about 0.4 mm to about 0.6 mm in width dimension,and about 0.085 mm to about 0.15 mm in height dimension.
 6. Themultilayer ceramic capacitor according to claim 1, wherein the height ofan effective portion that is a portion of the ceramic body where thefirst and second internal electrodes overlap each other in the heightdirection is referred to as A in the height direction; and the height ofa first outer layer portion that is a portion of the ceramic bodylocated between the first principal surface and the effective portion isreferred to as B in the height direction; and the height of a secondouter layer portion that is a portion of the ceramic body locatedbetween the second principal surface and the effective portion isreferred to as C in the height direction; each of ratios A/B and A/C iswithin the range of about 0.5 to about
 16. 7. The multilayer ceramiccapacitor according to claim 1, wherein the multilayer ceramic capacitoris about 0.9 mm or more and about 1.1 mm or less in length dimension,about 0.4 mm or more and about 0.6 mm or less in width dimension, andabout 0.085 mm or more and about 0.11 mm or less in a dimension inheight dimension; a maximum distance from the first principal surface toan internal electrode closest to the first principal surface among thefirst internal electrode and the second internal electrode in the heightdirection is referred to as T_(MAX); and a minimum distance from thefirst principal surface to the internal electrode closest to the firstprincipal surface in the height direction is referred to as T_(MIN); anda ratio (T_(MAX)−T_(MIN))/T is about 1.0% to about 5.0%.
 8. Themultilayer ceramic capacitor according to claim 1, wherein themultilayer ceramic capacitor is about 0.9 mm or more and about 1.1 mm orless in length dimension, about 0.4 mm or more and about 0.6 mm or lessin width dimension, and about 0.12 mm or more and about 0.15 mm or lessin a dimension in height dimension; a maximum distance from the firstprincipal surface to an internal electrode closest to the firstprincipal surface among the first internal electrode and the secondinternal electrode in the height direction is referred to as T_(MAX);and a minimum distance from the first principal surface to the internalelectrode closest to the first principal surface in the height directionis referred to as T_(MIN), and a ratio (T_(MAX)−T_(MIN))/T is about 1.3%to about 5.3%.
 9. The multilayer ceramic capacitor according to claim 1,wherein the multilayer ceramic capacitor is about 0.9 mm or more andabout 1.1 mm or less in length dimension, about 0.4 mm or more and about0.6 mm or less in width dimension, and about 0.18 mm or more and about0.20 mm or less in a dimension in height dimension; a maximum distancefrom the first principal surface to an internal electrode closest to thefirst principal surface among the first internal electrode and thesecond internal electrode in the height direction is referred to asT_(MAX); and a minimum distance from the first principal surface to theinternal electrode closest to the first principal surface in the heightdirection is referred to as T_(MIN); and a ratio (T_(MAX)−T_(MIN))/T isabout 1.5% to about 5.0%.
 10. The multilayer ceramic capacitor accordingto claim 1, wherein the multilayer ceramic capacitor is about 0.9 mm ormore and about 1.1 mm or less in length dimension, about 0.4 mm or moreand about 0.6 mm or less in width dimension, and 0.21 mm or more and0.23 mm or less in a dimension in height dimension, a maximum distancefrom the first principal surface to an internal electrode closest to thefirst principal surface among the first internal electrode and thesecond internal electrode in the height direction is referred to asT_(MAX); a minimum distance from the first principal surface to theinternal electrode closest to the first principal surface in the heightdirection is referred to as T_(MIN); and a ratio (T_(MAX)−T_(MIN))/T isabout 1.8% to about 5.9%.
 11. The multilayer ceramic capacitor accordingto claim 1, wherein the multilayer ceramic capacitor is about 0.9 mm ormore and about 1.1 mm or less in length dimension, about 0.4 mm or moreand about 0.6 mm or less in width dimension, and about 0.024 mm or moreand about 0.30 mm or less in a dimension in height dimension; a maximumdistance from the first principal surface to an internal electrodeclosest to the first principal surface among the first internalelectrode and the second internal electrode in the height direction isreferred to as T_(MAX); a minimum distance from the first principalsurface to the internal electrode closest to the first principal surfacein the height direction is referred to as T_(MIN); and a ratio(T_(MAX)−T_(MIN))/T is about 1.2% to about 6.0%.
 12. The multilayerceramic capacitor according to claim 1, wherein a distance in the lengthdirection from a position of a surface at a maximum dimension in theheight direction of the first external electrode on the first principalsurface to a position of a surface at a maximum dimension of the firstexternal electrode in the length direction on the first end surface isreferred to as E; and a distance in the length direction from theposition of the surface at the maximum dimension on the first endsurface to an edge end of the external electrode on the first principalsurface is referred to as e; a ratio E/e is about 0.243 or more andabout 0.757 or less.
 13. The multilayer ceramic capacitor according toclaim 1, wherein a maximum thickness and an average thickness of aportion of the first external electrode located on the first principalsurface are denoted respectively by D_(max) and D_(ave); andD_(ave)×250%≧D_(max)≧D_(ave)×120% is satisfied.
 14. The multilayerceramic capacitor according to claim 1, wherein a height dimension ofthe ceramic body is DT, a length dimension of the ceramic body is DL,and a width dimension of the ceramic body is DW, and a relationship(1/7)DW≦DT≦(1/4)DW is satisfied.
 15. The multilayer ceramic capacitoraccording to claim 1, wherein a height dimension of the ceramic body isDT and a relationship DT<about 0.15 mm is satisfied.
 16. The multilayerceramic capacitor according to claim 1, wherein the ceramic portion isabout 0.5 μm to about 10 μm in height.
 17. The multilayer ceramiccapacitor according to claim 1, wherein each of the first internalelectrode and the second internal electrode is about 0.2 μm to about 2μm in height.
 18. The multilayer ceramic capacitor according to claim 1,wherein the base layer is about 1 μm to about 20 μm in thickness. 19.The multilayer ceramic capacitor according to claim 1, wherein the Cuplated layer is about 1 μm to about 10 μm in thickness.
 20. Themultilayer ceramic capacitor according to claim 1, wherein the Cu platedlayer includes a plurality of plated films.